An artificial sandbar, also referred to as a submerged berm/mound or nearshore berm, is defined as the nearshore placement as an underwater berm for the purpose of beach nourishment or stabilization, or a combination of both. A series of physical experiments were performed to study on the interaction of regular waves and an artificial sandbar. The trapezoid-shaped sandbar physical model was made by resin model sand with a 3m-long flat crest and both seaward and landward slope of 1:10. Five regular wave conditions were generated, and the wave fluctuation series were collected by nine wave gauges. Sediment suspension process induced by waves can be captured by cameras, as well as the morphological change of sandbar. Meanwhile, an Optical Back Scattering (OBS) is set about 3m behind the sandbar to record the turbidity caused by the wave. The sandbar evolution were quantitatively obtained by video analysis method. The sandbar resulted in wave form changes by shoaling effect and inducing breaking with the reduction of wave height by 9.28%∼60.89%. The turbidity increases generally with the increase of incident wave height, and significantly increases due to strong turbulence after wave broken in plunging type. The cross-shore profile of sandbar has evolved significantly from a symmetrical shape to a highly asymmetrical shape with a steep landward slope and a mild seaward slope, due to erosion on the seaward slope and siltation on the landward slope in strong wave conditions. Meanwhile, the sandbar crest is eroded and becomes lower, the eroded pit becomes deeper and migrates landward with the wave propagation. In addition, an interesting asymmetrical two-peak shape of cross-shore profile of sandbar has been observed under a stronger wave with a plunging breaker.
Coastal erosion is a common phenomenon in China as well as in the world. The hard measures are implemented to protect coast such as building groins, offshore breakwaters and seawalls onshore, which turn out to cause erosion locally or downstream. Beach nourishment, as a soft measure, recharging the eroded coast with sediment from somewhere else has been found to be effective in avoiding the problems induced by hard structures. An artificial sandbar, also referred to as a submerged berm/mound or nearshore berm, is defined as the nearshore placement as an underwater berm for the purpose of beach nourishment or stabilization, or a combination of both (Dean and Dalrymple, 2002; Hamm et al., 2003).
